Refinery and petrochemical service

F22 is widely associated with chrome-moly process lines in hydroprocessing, hydrogen service, hot hydrocarbon circuits and other refinery units where the approved material class requires elevated-temperature strength. Actual suitability depends on process chemistry, hydrogen damage assessment, corrosion study and the adopted design code.

The flange is only one part of the circuit. Pipe, fittings, valves, bolting, gasket and weld metal must be selected as a compatible system, with any special hydrogen-service requirements written into the purchase specification.

Power generation and high-temperature steam

Power and industrial plants may use F22 flanges in steam, boiler auxiliary and high-temperature process systems designed around 2.25Cr-1Mo materials. Designers evaluate creep strength, thermal cycling, start-stop duty and joint loads rather than relying on a generic service-temperature claim.

For cyclic or heavily loaded connections, weld neck geometry is commonly preferred. The bore and weld end must match the pipe wall so the field weld can be made and examined under the qualified procedure.

F22 is not automatically corrosion-resistant

The chromium and molybdenum additions improve high-temperature behaviour compared with plain carbon steel, but F22 can still corrode in wet, acidic, chloride-bearing or contaminated environments. Internal corrosion, external corrosion under insulation and shutdown condensation require separate evaluation.

Coatings, insulation design, water exclusion and preservation may be needed for external protection. Process-side material selection remains the responsibility of the corrosion and piping design basis.

Procurement checklist for F22 flanges

• ASTM A182 F22 class/condition required by the project specification
• ASME B16.5 size, pressure class, type, facing and bore
• Heat treatment and mechanical-property evidence
• Hardness limits and test locations where specified
• PMI, MT or UT and third-party witness points
• EN 10204 3.1 documentation and heat-number traceability

Record the exact standard editions in the purchase order. Later edition changes should be reviewed, not assumed to be automatically equivalent.